pub struct MyValStc {
    a : i32,
    b : i32,
}

impl MyValStc {
    // 构造函数
    // pub fn new(username: String, email: String) -> Self {
    //     User { username, email }
    // }
    // pub fn init(a : i32, b : i32) -> Self {
    //     MyValStc {a, b}
    // }
    pub fn init(ca : i32, cb : i32) -> Self {
        MyValStc {
            a : ca, 
            b : cb
        }
    }
    pub fn add(&self) -> i32 {
        self.a + self.b
    }
}